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From "Andras Soltesz (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-3330) provide support for unique constraint over keys that include one or more nullable columns.
Date Fri, 10 Oct 2008 10:43:44 GMT

    [ https://issues.apache.org/jira/browse/DERBY-3330?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12638529#action_12638529
] 

Andras Soltesz commented on DERBY-3330:
---------------------------------------

Does anyone know when this and  DERBY-2212 make it to a release?

This is a very important part of functionality and it is really bad that it is not Oracle/PostgreSQL
compliant, since Derby is often used as a development database or single-user production database
in applications which use Oracle/PostgreSQL for multi-user production databases. With a behavioral
difference like this, Derby cannot be used in this scenario since those apps usually complex
enough to use this db feature.

I just bumped into it when my application became complex enough to use unique indexes on NULLable
columns. I have used the oracle-like unique index behavior since ages on Oracle and PG and
now I don't know how to support it on Derby. Obviously, it can be replaced only with complex
application logic.

> provide support for unique constraint over keys that include one or more nullable columns.
> ------------------------------------------------------------------------------------------
>
>                 Key: DERBY-3330
>                 URL: https://issues.apache.org/jira/browse/DERBY-3330
>             Project: Derby
>          Issue Type: New Feature
>          Components: SQL, Store
>    Affects Versions: 10.4.1.3
>         Environment: all
>            Reporter: Anurag Shekhar
>            Assignee: Anurag Shekhar
>         Attachments: BTreeController.diff, db2Compatibility-v2.diff, db2Compatibility.diff,
derby-3330-testcase.diff, derby-3330-UpgradeTests.diff, derby-3330.diff, derby-3330_followup_1.diff,
derby-3330_followup_1_modified.diff, derby-3330v10.diff, derby-3330v11.diff, derby-3330v12.diff,
derby-3330v13.diff, derby-3330v2.diff, derby-3330v3.diff, derby-3330v4.diff, derby-3330v5.diff,
derby-3330v6.diff, derby-3330v7.diff, derby-3330v8.diff, derby-3330v9.diff, derbyall_report.txt,
FunctionalSpec_DERBY-3330-V2.html, FunctionalSpec_DERBY-3330.html, sortercomments.diff, UniqueConstraint_Implementation.html,
UniqueConstraint_Implementation_V2.html, UniqueConstraint_Implementation_V3.html, UniqueConstraint_Implementation_V4.html
>
>
> Allow unique constraint over keys which include one or more nullable fields.  Prior to
this change Derby only supported unique constraints on keys that included no nullable columns.
 The new constraint will allow unlimited inserts of any key with one more null columns, but
will limit insert of keys with no null columns to 1 unique value per table.
> There is no change to existing or newly created unique indexes on null columns (as opposed
to unique constraints on null columns).  Also there is no change to existing or newly created
constraints on keys with no nullable columns.

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